<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
	* {
		margin: 0;
		padding: 0;
	}
	.nav {
		width: 250px;
		height: 20px;
		background-color: #cccc;
		text-align: center;
		
	}
	.nav ul {
		width: 100%;
		height: 100%;
	}
	.nav li {
		float: left;
		list-style: none;
		width: 50px;
		height: 20px;
		line-height: 20px;
	}
	</style>
</head>
<body>
	<div class="nav">
		<ul>
			<li>文件</li>
			<li>编辑</li>
			<li>选择</li>
		</ul>
	</div>
</body>
</html>